package com.justnow.offer;

public class DoubleCheck {

    private static volatile DoubleCheck instance;

    private DoubleCheck() {
    }

    public static DoubleCheck getInstance() {
         if (instance == null) {
             synchronized (DoubleCheck.class) {
                 if (instance == null) {
                     instance = new DoubleCheck();
                 }
             }
         }
         return instance;
    }
}
